President Bush says he objects to the bill because it takes choices "away from seniors to pay physicians."

The new law stops a 10.6 percent cut in Medicare payments to doctors, part of a scheduled cost-saving formula that went into effect July 1.

The money for the doctors will be taken from the government-subsidized Medicare Advantage program, which the Bush administration strongly supports.

Bush spiked the bill Tuesday, telling lawmakers they would be "taking choices away from seniors to pay physicians."

"I urge the Congress to send me a bill that reduces the growth in Medicare spending, increases competition and efficiency, implements principles of value-driven health care and appropriately offsets increases in physician spending," he said in his veto message.

The Senate voted 70-26 to enact the law over Bush's objections, the third time in his presidency that Congress has overridden his veto. The margin in the House of Representatives was a lopsided 383-41, well beyond the two-thirds majority needed.

The American Medical Association lobbied heavily for the bill, warning that its members could be forced to curtail seeing Medicare patients if the cuts went into effect. But insurers, which receive government subsidies to offer Medicare Advantage plans, warned that 2 million seniors could lose health benefits if it passed.

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A total of 21 Senate Republicans joined 47 Democrats and two independents in the override vote.

Supporters broke a GOP-led filibuster of the bill last week, aided by the dramatic return of Sen. Edward Kennedy of Massachusetts. Kennedy's vote came in his first appearance on the Senate floor since surgery to remove a brain tumor in early June.

Though he did not vote Tuesday, Kennedy praised his colleagues for overriding the "misguided" veto.

"It's a great vote, and a great day for America's seniors," he said in a written statement.

Those Republicans who opposed the bill argued that it would roll back many of the changes made to Medicare in 2003, when Congress created privately run, government-subsidized prescription drug coverage and expanded the role of private insurers in other coverage.

But critics of the 2003 reforms say Medicare Advantage subsidies end up costing more than the government would pay to cover the same people through regular Medicare, the federal health insurance program for seniors. The Congressional Budget Office estimates that the bill will reduce federal spending by $12.5 billion by 2013, largely by reducing Medicare Advantage enrollment.

Sen. Patty Murray, D-Washington, said the bill also made "vital improvements" by supporting rural health care and lowering fees for mental health care.

"Today, we can stand up for Medicare," she said. "We did it last week, when we came together and voted for this measure by a veto-proof margin, and I believe we can do it today by overriding that veto."

Congress had passed only two bills over Bush's objections: a $23 billion water-project legislation that the president vetoed in 2007 and a $300 billion farm bill he spiked in May.

The Medicare system pays for the health care of roughly 40 million elderly Americans. Rising health care costs have made Medicare a growing part of the federal budget, and the stress on the system is increasing as more baby boomers reach retirement age.

While the debate was raging over the bill, the AMA said the cuts could lead to a "meltdown" of the government's health care system for the elderly.

A recent survey by the group found that 60 percent of physicians will be forced to limit the number of new Medicare patients they can take on if the cuts go into effect.

"We stand at the brink of a Medicare meltdown. ... For doctors, this is not a partisan issue; it's a patient access issue," AMA President Nancy Nielsen said in a statement after last week's Senate vote.

The AMA ran radio and TV ads over the July Fourth congressional recess targeting 10 Republican senators, seven of whom are up for re-election.

The AARP, the nation's largest organization of retired people, and other groups also are weighing in against the cuts.

Gerald Harmon, a family physician who practices in Pawleys Island, South Carolina, said the cuts could lead to doctors taking fewer Medicare patients, making it difficult for the program's elderly patients to get the care they need.

"This Medicare access problem is a real issue, not just a political football," said Harmon, who said 35 percent of his patients were eligible for Medicare. "It affects your dad when he's sick. It affects my patients in my practice. This has to be addressed."